Progressive differentiation toward the long-lived plasma cell compartment in the bone marrow.

The longevity of plasma cells is dependent on their ability to access and reside in so-called niches that are predominantly located in the bone marrow. Here, by employing a traceable method to label recently generated plasma cells, we showed that homeostatic plasma cells in the bone marrow and spleen were continuously replenished by newly generated B220hiMHC-IIhi populations that progressively differentiated into B220loMHC-IIlo long-lived plasma cell (LLPC) populations. We also found that, in the bone marrow, germinal center (GC)-independent and GC-dependent plasma cells decayed similarly upon NP-CGG engagement, and both entered the B220loMHC-IIlo LLPC pool. Compared with NP+B220hiMHC-IIhi plasma cells, NP+B220loMHC-IIlo cells were more immobilized in the bone marrow niches and showed better survival potential. Thus, our results suggest that the adhesion status of bone marrow plasma cells is dynamically altered during their differentiation and is associated with provision of survival signals.

A case of Takayasu arteritis complicated with pulmonary infarction.

Takayasu arteritis (TAK) is a vasculitis that causes inflammation in the arterial walls of large blood vessels. The complication rate of pulmonary artery lesion in TAK has been reported to be relatively high. Severe pulmonary artery stenosis can cause pulmonary infarction in rare cases. A 48-year-old woman had experienced cough and fever persistently for 3 months and visited a city hospital. Contrast-enhanced computed tomography (CT) and positron emission tomography (PET)-CT scans revealed TAK complicated with left pulmonary artery lesion. Contrast-enhanced CT couldn't detect wall thickening in the left smaller bifurcated pulmonary artery branch, but PET-CT did reveal this inflammation. Several weeks after we initiated treatment with high-dose prednisolone, the patient's symptoms and inflammatory findings disappeared. PET-CT may be useful for evaluating the inflammation of the pulmonary artery in TAK, and high-dose steroid monotherapy as induction therapy may be effective for TAK complicated with pulmonary artery lesions causing pulmonary infarction.

Longer Prehospitalization and Preintubation Periods in Intubated Non-survivors and ECMO Patients With COVID-19: A Systematic Review and Meta-Analysis.

Purpose: There is no clear consensus on the clinical course of critical COVID-19 patients. We examined the clinical course among intubated survivors, non-survivors, and extracorporeal membrane oxygenation (ECMO) patients to reveal the standard clinical course and the difference among critical COVID-19 patients. Methods: In this systematic review and meta-analysis, we searched PubMed, Web of Science, and Scopus for original studies published until December 11, 2020, including case accumulation and clinical course reporting. Pregnant patients and children were excluded. We followed PRISMA guidelines and registered them with PROSPERO (CRD42021235534). Results: Of the 11,716 studies identified, 94 met the selection criteria, and 2,549 cases were included in this meta-analysis. The times from intubation to extubation and death were 12.07 days (95% confidence interval 9.80-14.33 days) and 10.14 days (8.18-12.10 days), respectively, and the ECMO duration was 14.72 days (10.57-18.87 days). The time from symptom onset to hospitalization (prehospitalization period) of intubated survivors, non-survivors, and ECMO patients was 6.15 (4.61-7.69 days), 6.45 (4.55-8.34 days), and 7.15 days (6.48-7.81 days), and that from symptom onset to intubation (preintubation period) was 8.58 (7.36-9.80 days), 9.14 (7.26-11.01 days), and 10.54 days (9.18-11.90 days), respectively. Sensitivity analysis showed that the time from intubation to extubation and death was longer in the US and Europe than in East Asia. Conclusion: For COVID-19, we hypothesize that prehospitalization and preintubation periods are longer in intubated non-survivors and ECMO patients than in intubated survivors. These periods may serve as a predictor of disease severity or death and support therapeutic strategy determination.